This invention relates to a device and method for combining a first yarn and a second yarn as the angle of delivery of the second yarn to the first yarn varies, and more particularly for combining a fine denier yarn with a heavier denier yarn.
It is often useful or necessary to combine a fine denier yarn with a higher denier yarn, staple or tow, as in plying and twisting operations. For example, it has been found that the build-up of static electricity in nylon carpets to uncomfortable levels can be prevented or dissipated by combining the nylon carpet yarns during manufacture of the carpet with fine denier metallic yarns, including yarns which are wholly metal and yarns which are metallized, that is, metal coated. Silvered nylon yarn is an example of such metallic yarns.
The handling of metallic or non-metallic fine yarns, especially when they are to be combined with higher denier yarns such as carpet yarns, present special problems to the carpet manufacturer. The fine yarns, lacking the weight and/or bulk of the normally heavier carpet yarns, do not readily feed or "run" through delivery tubes, eyeboards, eyelets and other portions of carpet manufacturing machinery. "Runnability" of such yarns is therefore said to be poor. Fine yarns also require careful attention to yarn package geometry and spatial relationships between the packages and delivery mechanism for combination with higher denier yarns. Special accommodation must be made for the ballooning characteristics of fine yarns and the sloughing off and tendency of such yarns to snarl when delivered from a cone-shaped package into combination with a heavier yarn. For example, in the manufacture of tufted carpets, when it is attempted to lay in the fine yarns in parallel with the heavier yarns in the yarn sheet just prior to tufting, the fine yarns cross over to adjacent yarns in the yarn sheet with consequent undesirable irregularity and even snarling of the yarn sheet.
The problem is not solved by the usual methods of combining the yarns prior to formation of the yarn sheet. Serious difficulty is experienced in maintaining an efficient contact angle between the two yarns at the point of combination since the transfer of a tail of the heavier yarn from one package to another in the magazine of yarn packages commonly utilized in such systems, prevents continuity of the combining operation. The operation has to be stopped while the package of fine yarn is reoriented to accommodate the new package of heavier yarn. Also, the yarn packages must be rearranged in the creels to provide space for ballooning of the fine yarn, thus requiring substantial and expensive modification of creels and other apparatus. Further, the angle of delivery of the yarns to each other, from any package in the system, continually changes as the yarns unwind from their holders. Considerable care must therefore be taken to avoid snagging due to "tight spots," i.e., more tightly wound yarns on the holders.
The foregoing problems are greatly compounded when the fine denier yarn is a metallic yarn. Not only does the metallic yarn tend to become fouled at undesirable points in a yarn sheet in a tufting operation as a result of static build-up in the sheet, but also there is severe binding, snarling and skinning in the eyelets and delivery tubes through which the metallic yarn passes on its way to combination with the heavier yarn in a yarn sheet. When it is attempted to combine the yarns, prior to formation of the yarn sheet, especially when using magazined coneshaped yarn holders, sloughing and snarling are even more severe. Separate delivery systems for each of the yarns to a yarn sheet or other work station has to be abandoned in favor of some other approach which will also enable the carpet manufacturer avoid substantial modification of existing apparatus.